Recently, Software Defined Network (SDN) has been widely recognized as the next generation network management scheme in the packetized data communication era. Current SDN defines SDN native control message and protocol, OpenFlow is the well-known standard for the control message, but it may not be true to determine the protocol is the only choice applicable to the SDN concept. Hereinafter use “SDN control message” as a generalized protocol name which can be used for SDN.
In the origin of the OpenFlow, it has been assumed to control a standalone OpenFlow device which will replace today's Layer two (2) switches (L2SW) and routers; all of them are not in a form of multi node system. Compare with the L2SWs and routers, access network system is comprised of a CO and more than one CPE and they are tightly coupled in its configuration. For example, the Passive Optical Network (PON) technology which is used for the Fiber To The X (FTTX, X stands various types of delivery method) service consists from an Optical Line Terminator (OLT) as a CO device and plural Optical Network Unit (ONU) as a CPE device. The OLT controls the ONUs with specific control protocols, which are known as Multi-Point Control Protocol (MPCP) and Operation Administration and Maintenance (OAM) protocol. If operator wants to apply the current OpenFlow control message to those devices, both the OLT and the corresponding ONU need to be OpenFlow native devices.
Although applying an integrated SDN management across the network including the access node can maximize the benefit in the CPAEX and the OPEX, network operators have deployed the legacy access nodes in large and then it becomes a significant disadvantage for operators who want to use OpenFlow because each of the standalone device must be a standalone SDN native device. This situation will enforce operators to replace the whole legacy access nodes if they plan to manage them under integrated SDN management, especially the replacement of the whole CPE in the customer premises will cause a severe service disruption.
From this background, it is proposed to virtualize an access node as a single SDN native node, and thereinafter, the SDN Management System can control the access node without being aware the actual type of device but control and manage it as the SDN native device.